Conventional hydroturbines were usually operated by virtue of water potential energy enhanced by a dam so that water energy can be effectively utilized. If there is no such dam, the conventional hydroturbine will have low efficiency to convert water flow energy into mechanical energy. Although huge water energy exists in rivers and seas, most cannot be utilized as most of the places are not suitable for constructing dams. As height of water head has great influence on performance of the hydroturbine, low-head hydroturbine can hardly apply to the river and sea where the dams cannot be constructed.
On the other hand, a water pump is essential equipment in agricultural irrigation and breeding, and it usually pumps water one direction, but cannot perform in a reversible direction.